VDO Speedo Calibration Issue

[Lawler]

I have been messin around with my VDO gauge for 2 weeks now and just can't get it right. This is what I have:

1. Tremec TKO 600
2. 3:73 rear
3. Three wire hall effect sensor

I have run the auto-calibration many times and I get a different pulse number each time. Not just a few pulses off each time, but a major variance in the data with each mile run (slowly no more than 20 mph). The gauge seems to be all over the place. Will hold steady for a while then bom 120mph! mopst of the time it wont get over 40 mph. Pulse numbers vary from 4500 to 16550. They fall all over the place between these hi and low data points.

I installed the 1N4005 diode inline with the red signal wire today and basically got the same responce from the speedo. The speedo is wired to a three wire hall effect sensor. The pulse auto-calibration number was 5550. At first it seemed to be right but when I got on a good road it would max out at 60 when I know better ( the scenery was stretching a bit)

Any assistance would be greatly appreciated.

Kinton